test: multi-session same-sensor schedules accumulate (sum)

[sankalpsthakur]

Description

• Add regression test for multi flex-model sessions sharing one power sensor
• Assert schedules are summed (not overwritten) after Fix: StorageScheduler to correctly combine multiple sessions targeting the same sensor #1948
• Non-overlapping windows: per-half + total energy assertions (overwrite would zero the first half)
• Overlapping windows: equal capacity pre-allocation; combined schedule still sums
• Changelog: skipped (test-only; Fix: StorageScheduler to correctly combine multiple sessions targeting the same sensor #1948 already changelogged the behaviour)

Fixes #1947

Completes the regression-test slice discussed after #1948. Documentation example deferred pending product discussion (nhoening).

Core fix was #1948 (storage_schedule[sensor] += ...). This PR only locks that in with focused tests maintainers asked for (high value / low effort).

Impact

Severity: silent schedule loss — with multiple flex-model entries on one power sensor (common for EV sessions on a single charge point), only the last session's schedule was kept. Earlier sessions were overwritten with no error.

Before #1948: two non-overlapping 2 kWh sessions on one sensor → ~2 kWh delivered (first half zeros). After: ~4 kWh (both halves active).

Look & Feel

N/A (test-only).

Non-overlapping

Window	Session	Power
hours 0–1	session 1	1 kW
hours 2–3	session 2	1 kW

• Correct (sum): schedule ≈ [1, 1, 1, 1] kW, total energy 4 kWh
• Overwrite (pre-Fix: StorageScheduler to correctly combine multiple sessions targeting the same sensor #1948): would keep only the last session (~2 kWh, zeros in the first half)

Overlapping (capacity pre-split)

Both sessions active all 4 hours at 0.5 kW each (pre-allocation per Flix6x on #1947):

• Correct (sum): [1, 1, 1, 1] kW (~4 kWh)
• Overwrite: ~0.5 kW (~2 kWh)

How to test

pytest \
  flexmeasures/data/models/planning/tests/test_storage.py::test_multiple_sessions_same_sensor_accumulate_schedules \
  flexmeasures/data/models/planning/tests/test_storage.py::test_multiple_sessions_same_sensor_accumulate_overlapping_windows \
  -v

Further Improvements

• Scheduling docs example for multi-session / same-sensor modelling (power capacity pre-allocation when sessions overlap) — left open per discussion on StorageScheduler overwrites schedules when multiple sessions use the same sensor #1947

Related Items

• Fixes StorageScheduler overwrites schedules when multiple sessions use the same sensor #1947 (regression-test slice; core behaviour already fixed in Fix: StorageScheduler to correctly combine multiple sessions targeting the same sensor #1948)
• Core fix: Fix: StorageScheduler to correctly combine multiple sessions targeting the same sensor #1948
• Multi-asset schedule produces unexpected results #2329 (multi-asset unexpected schedules) is a separate constraint-modelling issue; same-sensor accumulation is prerequisite but not sufficient for that report

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Sign-off

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on code under GPL or other license that is incompatible with FlexMeasures

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[read-the-docs-community]

Documentation build overview

📚 flexmeasures | 🛠️ Build #33713389 | 📁 Comparing 6632b8a against latest (9acc4eb)

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• changelog.html
• genindex.html
• _autosummary/flexmeasures.data.models.generic_assets.html
• _autosummary/flexmeasures.data.models.planning.html
• _autosummary/flexmeasures.ui.views.assets.utils.html
• api/v3_0.html
• cli/change_log.html